1. Technical Field
The present invention relates to subscriber's telephone circuits and more particularly to a dual timing circuit for use with a subscriber's telephone circuit that simulates in response to manual switch operations the placement of the subscriber's telephone "on-hook" for different predetermined periods of time.
2. Background Art
In recent years, demand has been created for electronic communication systems that provide a number of cost effective automated features. Of particular emphasis in this area have been the development of a number of new private automatic branch exchange systems (PABX's) that include a number of built in features not previously available in PABX systems. Many of these features are activated at the subscriber's telephone instrument by means of operation of the hookswitch. Among these features are a call transfer arrangement whereby operating the hookswitch for a defined amount of time, i.e. 300 milliseconds to 800 milliseconds, the PABX may be operated to facilitate transfer from a call from one subscriber's instrument to another within the PABX system. On the other hand if the subscriber wishes to place a new call such PABX's require that the subscriber's set be for a minimum time of three to seven seconds in the "on-hook" condition, to recognize the request and then supply dial tone for the placement of a new telephone call. The current generation of electronic PABX systems will not recognize a new call before this minimum time "on-hook" .
In many instances the accurate gauging of the appropriate time to go to the "on-hook" condition for call transfer or for placement of a new call are difficult to judge for the subscriber and therefore a call may be lost rather than transferred or if the person wishes to initiate a new call, the transfer facility may have been activated instead of preparing the system for placement of a new call. Some modern subscriber's instrument incorporating microprocessor control are able to provide such control of the "on-hook" condition however the method for achieving same is costly. Such an instrument is the FEATURE-FONE.RTM. telephone manufactured by GTE Business Communications Systems, Incorporated.
Accordingly, it is the object of the present invention to provide a new and improved dual timing circuit for use in a subscriber's telephone circuit wherein response to operation of one of two momentary contact pushbuttons, the "on-hook" condition is achieved for a predetermined period of time, effective to either provide the desired transfer feature or in response to the operation of the other pushbutton provide for the initiation of a new call.